Use a recipe that yields no more than a one pound batch. Even using a blender, accuracy in measuring is still a necessity, but exactness of temperatures for the lye and fat is not as critical.

Cold softened or rain water must be used to dissolve the lye. The lye is ready for mixing when it turns clear.

The fat should be just melted at which point, everything including fragrances and colorants, goes together in the blender. Remember to carefully pour in the lye to avoid splashing. The blender shouldn't be much more than half full. Before turning on the blender and mixing at LOWEST speed, make absolutely certain the lid is securely in place. Mix at the lowest speed, checking often for tracing.

Before checking for trace, turn off the blender and allow to sit a few seconds before removing the lid in case the soap mixture "burps" and splashes. At the thin trace stage, stir gently to remove bubbles and pour soap into individual molds. If you wait until full trace, the air bubbles can not escape.

While using a blender does not allow for big batches of soap, it has three distinct advantages:

1) Much shorter time to the thin trace stage. Instead of 30 - 40 minutes, it might require only 30 seconds. Yes, seconds!
2) No thermometers are required.
3) The blender literally beats the lye water into the fats producing a much smoother mixtureso the chances of separation are greatly reduced.

Using a blender is one way to achieve a floating bar of soap by deliberately whipping air into the mixture. This requires allowing the soap to mix to the over-trace stage which makes it trickier to pour. I would suggest first perfecting making soap the traditional way using thermometers and understanding what the trace stage looks like before attempting this method. Nothing is hard if you're familiar with it and familiarity only takes practice.